The electrolyte used in an electrochemical battery cell is either alkaline, such as potassium hydroxide or sodium hydroxide, or acidic. During the anode or cathode electro-chemical process that takes place in each cell, gasses are normally produced. These gasses consist mostly of hydrogen and oxygen and must be vented from the cell in order to prevent a high-pressure buildup inside the cell. In most silver-zinc alkaline cells, for example, the cell container or casing is fitted with a pressure regulator that vents gasses prior to excessive pressure build-up inside the cell.
An undesirable event that often occurs during the venting process is the escape of liquid electrolyte from inside the cell through the pressure regulator. This free electrolyte that escapes from the cell can create certain serious problems. For example, the electrolyte can produce unwanted electrode to battery case voltages or voltages between the cell electrodes within the battery. The normal method to prevent these undesired current paths is to place an absorbent material over the pressure regulator. Based on the available space within the battery cells, this is not always possible and cell short circuits have occurred in instances even where the absorbent material is used.
It is therefore an important object of this invention to provide a pressure relief valve that vents gasses while retaining the liquid electrolyte inside the cell.